Late Pliocene climate variability on Milankovitch to millennial time scales: A high-resolution study of MIS100 from the Mediterranean

Abstract

Astronomically tuned high-resolution climatic proxy records across marine oxygen isotope stage 100 (MIS100) from the Italian Monte San Nicola section and ODP Leg 160 Hole 967A are presented. These records reveal a complex pattern of climate fluctuations on both Milankovitch and sub-Milankovitch timescales that oppose or reinforce one another. Planktonic and benthic foraminiferal δ 18O records of San Nicola depict distinct stadial and interstadial phases superimposed on the saw-tooth pattern of this glacial stage. The duration of the stadial–interstadial alterations closely resembles that of the Late Pleistocene Bond cycles. In addition, both isotopic and foraminiferal records of San Nicola reflect rapid changes on timescales comparable to that of the Dansgard–Oeschger (D–O) cycles of the Late Pleistocene. During stadial intervals winter surface cooling and deep convection in the Mediterranean appeared to be more intense, probably as a consequence of very cold winds entering the Mediterranean from the Atlantic or the European continent. The high-frequency climate variability is less clear at Site 967, indicating that the eastern Mediterranean was probably less sensitive to surface water cooling and the influence of the Atlantic climate system. Concomitant changes in the colour reflectance of ODP Site 967 and the calcium carbonate record of San Nicola probably indicate that part of the high-frequency climate variability (3–5 kyr) in the eastern Mediterranean is related to changes in Saharan dust supply. Evidently, enhanced dust deposition in the Mediterranean correlates with the cold intervals of the millennial-scale D–O oscillations suggesting that the Atlantic pressure system may have played a critical role in varying the wind strength and/or aridification of northern Africa.